270 (number)

270 (two hundred [and] seventy) is the natural number following 269 and preceding 271.

In mathematics

• 270 is a harmonic divisor number
• 270 is the fourth number that is divisible by its average integer divisor (sequence A007340 in OEIS)
• 270 is a practical number, by the second definition
• The sum of the coprime counts for the first 29 integers is 270
• 270 is a sparsely totient number, the largest integer with 72 as its totient
• Given 6 elements, there are 270 square permutations  A003483
• 10! has 270 divisors
• 270 is a Harshad number in base 10
• 270 is the smallest positive integer that has divisors ending by digits 1, 2, …, 9.

In other fields

• The year 270 BC
• The year 270 AD
• The caliber of the .270 Winchester rifle
• The number of U.S. Electoral College votes needed to be President of the United States
• The average number of days in human pregnancy
• A pseudonym for Konami musician Naoki Maeda
• One of a number of secondary Interstate highways connecting to Interstate 70: Interstate 270

271–279

271

• Two hundred [and] seventy-one prime, twin prime with 269, cuban prime, centered hexagonal number, sum of eleven consecutive primes (7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43).

272

• Two hundred [and] seventy-two 272 = 2⁴·17, sum of four consecutive primes (61 + 67 + 71 + 73), Euler number, primitive semiperfect number, pronic number

273

• Two hundred [and] seventy-three has its own article.

274

• Two hundred [and] seventy-four = 2·137, tribonacci number, Smith number, nontotient, noncototient, centered triangular number

275

• Two hundred [and] seventy-five 275 = 5²·11

276

• Two hundred [and] seventy-six has its own article.

277

• Two hundred [and] seventy-seven Perrin number, self number

278

• Two hundred [and] seventy-eight 278 = 2·139, nontotient

279

• Two hundred [and] seventy-nine 279 = 3²·31 Every positive integer is the sum of at most 279 eighth powers. See Waring's problem